Describe a situation that others didn’t tell you the whole truth.
You should say:
what that situation was
who was involved
why they didn’t tell you the whole truth
and explain how you felt when you found out you were not told the whole truth.
Let me tell you about the experience I met when I bought a new microwave oven several months ago in a big shopping mall. It was a quite expensive microwave so I asked the salesman whether it was a brand new one. She replied to me that it was never be used before. So I took it home, but after trying for several times, I found the equipment was not working as it claimed to be. The food in the oven was still cold after heated for even 5 minutes. It seemed to be something wrong with the equipment.
Therefore, I telephoned the after-sales department in that shop to tell them the faulty machine. They sent a technician to my home to examine the machine. That man admitted that my microwave was once sold to others before, and returned afterwards, so I bought a broken one, and I felt I was cheated and fooled by that salesman obviously. I was really angry with that salesman, I thought I trusted her, but she didn’t tell me the truth. That crafty salesman really made me sick. So I returned that microwave immediately and made my mind that I would never buy anything from that shopping mall again.